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West Nile Virus

Mosquitoes are annoying. They can also make you sick. When a mosquito bites a bird infected with West Nile, it gets the virus. The infected mosquito can then spread West Nile virus when it bites people. You can reduce your risk of being infected by West Nile virus by preventing mosquito bites. There are no medications or vaccines to prevent or treat West Nile virus.

What is West Nile virus?

West Nile virus is an infection that can make you sick. Most people get West Nile virus after being bitten by an infected mosquito. The mosquitoes get infected by feeding on birds that have the virus. They can then spread the virus to humans and to other animals.

Did you know? Mosquitos are most active at dawn (first light) and dusk (just before dark).

What can I do to prevent West Nile virus?

The easiest and best way to avoid West Nile virus is to avoid mosquito bites. Try the following tips.

Cover exposed skin

When you are outside, wear long pants and loose-fitting shirts with long sleeves. You should also wear socks and a hat. Mosquitoes are attracted to dark colours, so stick with light-coloured clothing whenever you can.
A mosquito net over your hat or cap can protect your head, face and neck from bites.

Use insect repellent (bug spray)

When you are outside, you should use insect repellents (bug sprays and lotions) that contain DEET. DEET is a brand of diethyltoluamide that is a colourless oily liquid that keeps bugs like mosquitoes and ticks away. You should always follow the directions on the container.

If you use bug spray rather than lotion, be extra careful when putting it on children. To avoid getting bug spray in your mouth or eyes, try spraying it into your hands first. Then rub it onto your face.

Get rid of mosquito breeding areas

Mosquitoes like standing water (water that does not move or flow). Get rid of standing water around your home by following these tips:

drain or dry off water in old tires (even tire swings), rainwater barrels, children's toys, flower pots and wading pools

tip fishing boats and gear onto their sides

replace the water in your pet dishes at least two times a week

Keep mosquitos out of your home

How is West Nile virus spread?

Most people get West Nile virus when an infected mosquito bites them.

In nature, West Nile virus cycles between mosquitoes and birds. Some infected birds can develop high levels of the virus in their bloodstream and mosquitoes can become infected by biting these infected birds. After about a week, infected mosquitoes can pass the virus to more birds when they bite.

Mosquitoes with West Nile virus also bite and infect people, horses and other mammals. However, humans, horses and other mammals are 'dead end' hosts. This means that they do not develop high levels of virus in their bloodstream, and cannot pass the virus on to other biting mosquitoes. In very rare cases, people can get West Nile virus from blood transfusions, tissue transplant or a mother-to-child transfer. If you need a blood transfusion, remember that the risk of getting West Nile virus this way is very low. Canadian Blood Services tests all donated blood to ensure its safety. There is no risk of getting West Nile virus when you give blood.

You cannot catch West Nile virus by touching or kissing a person with the virus. You should not worry about catching West Nile from nurses or caregivers who treat someone with the virus. You cannot catch West Nile virus by touching an infected animal--unless there is blood-to-blood contact.

What are the symptoms?

Most people who are infected with West Nile virus do not get sick at all. According to the Centers for Disease Control and Prevention, between 70-80% of people who become infected do not develop any symptoms. Some people get mild symptoms like a low fever, headaches, tiredness or body aches. People usually get symptoms between three and 14 days after they are bitten by an infected mosquito. A few people get very sick from West Nile virus.

You should see a nurse or visit the hospital if you have these more serious symptoms:

How is West Nile virus treated?

There is no special treatment, medicine or even a cure for West Nile virus.

If you have mild symptoms (such as a low fever and some body aches), then you should get better in a few days. If you have more serious symptoms (high fever or vomiting), you should see a doctor or nurse right away. It is important that you prevent other more serious health problems from starting if you get sick with the West Nile virus.

First Nations and Inuit risk

Health workers can provide information sessions to First Nations residents, Chiefs and councils, leaders and community workers. They can also recommend ways to lower your risk of getting West Nile virus-including the use of insecticides. A band council resolution is required before insecticides can be used.

Eating birds or animals that are infected with West Nile virus

There is no evidence that people can get West Nile virus from eating infected birds or animals that are fully cooked.

Avoid blood-to-blood contact with wild animals

If you hunt or skin wild animals, remember that West Nile virus can spread through blood-to-blood contact. To protect yourself:

always wear gloves when you handle dead animals

always make sure any open wounds on your hands are covered

you need to wash your gloved hands and then wash your bare hands. This should be done every time you handle any dead animal. This will help protect you from any disease the animal might have.

Risk areas

Risk areas are based on laboratory-confirmed cases of West Nile virus in birds, animals (such as horses), mosquito pools or people.

Low-risk areas: A low-risk area hasno confirmed cases of West Nile.

Medium-risk areas: A medium-risk area has one reported case of West Nile virus during the last year. An area can also be listed as medium risk if it is next to a high-risk area.

High-risk areas: A high-risk area is where West Nile virus has been confirmed this year.

What can I do to help?

Although you can catch the West Nile virus from a mosquito, the mosquito caught the virus from biting a bird. If you are finding dead birds in your community, it may be a sign that the West Nile virus is in your area. Here is what you can do to help.

Report dead birds

If you find a dead bird, do not handle its body with your bare hands. You should always wear rubber gloves when touching any dead birds or animals. Dead birds may carry disease. If a dead bird is reported on a reserve, environmental health officers may come to collect it. Then they will send it to a laboratory for testing.

The types of birds to collect for testing commonly include crows, jays, ravens and magpies. However, bird types can vary from region to region, as well as from province to province and territory to territory. To find out if any birds are being collected in your area, contact your:

environmental health officer

community health centre, or

nursing station

Surveillance

Surveillance means checking to see if West Nile virus has been found in people, birds and mosquito pools. From May to October, the Public Health Agency of Canada produces the weekly Maps & Stats: West Nile Virus Monitor.